Conventionally, there is known a technology to reduce an amount of traffic in a network thereby reducing electric power consumed by a network device. As an example of such a technology, there is known a CDN (Content Delivery Network) technology to place a copy of content in a plurality of servers on a core network or a metro network and deliver the content from the server geographically closest to a user. In a network to which the CDN technology is applied, content delivery is processed at the network edge; therefore, an amount of traffic flowing through the network is reduced, and electric power consumed by a network device is reduced.
Furthermore, there is known a CCN (Content Centric Network) technology to provide a cache function to a router on a network thereby easing restrictions on a cache location of content. In a network to which the CCN technology is applied, a router of a core network or a metro network caches a replica of content and delivers the cached content, thereby reducing an amount of traffic flowing through the network and reducing electric power consumed by a network device and a cost of device deployment.
Patent document 1: Japanese Laid-open Patent Publication No. 2010-199736
However, in the above-described technology to cause a server or a router to cache a replica of content, a cache location is set by taking into account only an amount of traffic on a network; therefore, there are problems that electric power consumed by the network and a cost associated with device deployment cannot be reduced appropriately.
Namely, when a server or a router caches a replica of content, power consumption associated with the use of a memory arises even if the server or router does not deliver the content, or a cost associated with deployment of the memory arises. Therefore, when a network causes many servers or routers to cache a replica of content, an amount of electric power and a device cost for caching the replica of content are increased, and consumed electric power and the device cost cannot be reduced appropriately.